1. Field of the Invention
This invention relates to an improved method of manufacturing a silicone elastomeric emulsion of high solids content.
2. Description of the Prior Art
Silicone elastomeric emulsions are described in U.S. Pat. No. 4,221,688, issued Sept. 9, 1980, to Johnson et al. This patent teaches a silicone emulsion which provides an elastomeric product upon removal of the water. The dispersed phase consists essentially of an anionically stabilized hydroxylated polydiorganosiloxane which contains about 2 silicon-bonded hydroxyl groups per molecule, an organic tin compound, and a colloidal silica. The emulsion can also contain other fillers including clays, aluminum oxide, quartz, calcium carbonate, zinc oxide, and mica. The method of manufacture prepares an emulsion of a hydroxylated polydiorganosiloxane, adds colloidal silica and organic tin compound, and adjusts the pH of the resulting emulsion to a range of 9 to 11.5 inclusive. This patent teaches that if the emulsion without the organic tin compound is stored, such as for five months, a useful film is formed upon drying. By adding the organic tin compound, the emulsion need only be stored for one to three days before a useful elastomeric product is formed upon drying.